Time relationships between magmatism, tectonics and metamorphism in three plutonic belts in Southern Tibet: new K-Ar data

Debon, F.; Zimmermann, J.-L.; Guohue, Liu; Chengwei, Jin; Xu, Runsheng

doi:10.1007/bf01824894

Cited by 22 publications

(8 citation statements)

References 15 publications

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“…The consistency of our muscovite and biotite ages with earlier K/Ar and 40 Ar/ 39 Ar data from both granites (Krummenacher, 1971;Dietrich and Gansser, 1981;Debon et al, 1985;Maluski et al, 1988) leads us to conclude that the Mustang granite and the Kula-Kangri granite cooled through the 300-350 °C temperature range at 15-17 Ma and 11-13 Ma, respectively. As first pointed out by Villa and Oddone (1988), and on the basis of these new data, together with published data, it appears that cooling ages of High Himalayan leucogranites decrease eastward from 22-18 Ma to 11-13 Ma over a distance of 1,500 km from Zanskar to Bhutan (Fig.…”

Section: Ar/ 39 Ar Cooling Ages Of the Leucogranitessupporting

confidence: 72%

“…From Zanskar to Everest, numerous ages between 22 and 15 Ma have been reported using different isotopic systems ( 40 Ar/ 39 Ar , U/Pb, Rb/Sr) related to the M2 event and motion along the Main Central thrust and the South Tibetan detachment system (Hubbard et al, 1991;Inger and Harris, 1992;Metcalfe, 1993;Parrish and Hodges, 1992;Spring et al, 1993;Vannay and Hodges, 1996). In the Kangmar dome, there is also evidence of Miocene 40 Ar/ 39 Ar cooling ages around 20-13 Ma, which are assigned to the M2 metamorphic event (Debon et al, 1985;Chen et al, 1990) (Table 1).…”

Section: Geochronological Evolution Of the Higher Himalayamentioning

confidence: 92%

“…1). (Dietrich and Gansser, 1981;Debon et al, 1985;Maluski et al, 1988;Stern et al, 1989;Copeland et al, 1990;Inger and Harris, 1992;Metcalfe, 1993;Sorkhabi et al, 1993Sorkhabi et al, , 1996Guillot et al, 1994;Hodges et al, 1994).…”

Section: Ar/ 39 Ar Cooling Ages Of the Leucogranitesmentioning

confidence: 96%

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Contrasting metamorphic and geochronologic evolution along the Himalayan belt

Guillot¹,

Allemand²,

Fort³

1999

Himalaya and Tibet: Mountain Roots to Mountain Tops

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Systematic different pressure-temperature-time paths are recorded along the internal zone of the Himalayan orogen. High-pressure rocks rapidly exhumed during the Eocene and Oligocene are restricted to the western part of the Himalayan belt. Farther to the east, both in the North Himalayan Crystalline massif sand in the High Himalayan Crystalline slab, there are upper amphibolite facies rocks, which were unroofed during the Miocene. In the High Himalayan Crystalline slab, a systematic decrease in mica 40 Ar/ 39 Ar cooling ages can be correlated with the degree of low-pressure anatexis to the east. The observed contrasts in both the metamorphic and geochronologic evolution along the Himalayan belt can be related to the counterclockwise rotation of the Indian plate during the India-Asia collision. Such rotation, together with a shallower dip of the intracontinental subduction plane to the east, would explain the delay in nappe stacking, a warmer thickened upper crust, and the observed decrease in ages from west to east.

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Section: Ar/ 39 Ar Cooling Ages Of the Leucogranitessupporting

confidence: 72%

Section: Geochronological Evolution Of the Higher Himalayamentioning

confidence: 92%

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Contrasting metamorphic and geochronologic evolution along the Himalayan belt

Guillot¹,

Allemand²,

Fort³

1999

Himalaya and Tibet: Mountain Roots to Mountain Tops

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“…Such an early contact may have induced a Late Cretaceous to Paleocene phase of south-verging thrusting onto northwestern India (Searle, 1986(Searle, , 1988Searle et al, 1987Searle et al, , 1988Searle et al, , 1990) and a metamorphic phase at about 67 Ma in the internal zones of the Western Himalayan Syntaxis (Treloar and Rex, 1990). A further thermal event at about 50 Ma, observed in the same region (Treloar and Rex, 1990) and also in the Gangdese belt of Southern Tibet (Debon et al, 1985), may be related to completion of suturing.…”

Section: Geological Record Of the Convergence Zonementioning

confidence: 96%

Constraints on the India-Asia Convergence: Paleomagnetic Results from Ninetyeast Ridge

Klootwijk¹,

Gee²,

Peirce³

et al. 1991

Proceedings of the Ocean Drilling Program, 121 Scientific Results

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This study details the Late Cretaceous and Tertiary northward movement of the Indian plate. Breaks in India's northward movement rate are identified, dated, and correlated with the evolution of the India-Asia convergence. Paleolatitudinal constraints on the origin of Ninetyeast Ridge are discussed, and limited magnetostratigraphic detail is provided.Nearly 1500 sediment and basement samples from Sites 756, 757, and 758 on Ninetyeast Ridge were studied through detailed alternating field and thermal demagnetization. Primary and various secondary magnetization components were identified. Breakpoint intervals in the primary paleolatitude pattern for common-Site 758 were identified at 2. 7, 6.7,18.5, about 53, 63.5-67, and 68-74.5 Ma. Only the breakpoint interval at about 53 Ma reliably reflects a reduction in India's northward movement rate. The onset of this probably gradual slowdown was dated at 55 Ma (minimal age) based on the intersection of weighted linear regression lines. At the location of common-Site 758, northward movement slowed from 18-19.5 cm/yr (from at least 65 to 55 Ma) to 4.5 cm/yr (from 55 to at least 20 Ma). Reanalysis of earlier DSDP/ODP paleolatitude data from the Indian plate gives a comparable date (53 Ma) for this reduction in northward velocity.Comparison of our Ninetyeast Ridge data and Himalayan paleomagnetic data indicates that the initial contact of Greater India and Asia may have already been established by Cretaceous/Tertiary boundary time. The geological record of the convergence zone and the Indian plate supports the notion that the Deccan Traps extrusion may have resulted from the ensuing deformation of the Indian plate. We interpret the breakpoint at 55+ Ma to reflect completion of the eastward progressive India-Asia suturing process.Neogene phases in the evolution of the convergence zone were correlated with significant changes in the susceptibility, NRM intensity, and lithostratigraphic profile of Site 758. These changes are interpreted to reflect and postdate tectonic phases in the evolution of the wider Himalayan and southern Tibetan region. The changes were dated and interpreted as follows: 17.5 Ma, initial uplift of the Higher Himalaya following initiation of intercontinental underthrusting; 10-10.4 Ma, increased uplift and onset of Middle Siwaliks sedimentation; 8.8 Ma, probable reduction in influx corresponding with the Nagri Formation to Dhok Pathan Formation changeover; 6.5 Ma, major tectonic phase evident throughout the wider Himalayan region and northern Indian Ocean; 5.1-5.4 Ma, onset of oroclinal bending of the Himalayan Arc, of extensional tectonism in southern Tibet, and of Upper Siwalik sedimentation; 2.5-2.7 and 1.9 Ma, major phases of uplift of the Himalayan and Tibetan region culminating in the present-day high relief.The basal ash sequence and upper flow sequence of Site 758 and the basal ash sequence of Site 757 indicate paleolatitudes at about 50°S. These support a Kerguelen hot spot origin for Ninetyeast Ridge. Consistently aberrant inclinations in the basa...

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“…Edwards & Harrison 1997;Harrison et al 1998, and references therein;Whittington & Treloar 2002). Melt production in the Himalaya was formerly regarded as a short discrete event (Debon et al 1985(Debon et al , 1986Harrison et al 1998), or several events (Guillot & Le Fort 1995), that created the High Himalayan Leucogranites alone, and/or separately, the Northern Himalayan Granites. More recently, however, with constraints upon the geometry of Himalayan orogen provided by controlled-source CMP reflectors and wideangle velocity structure (Zhao et al 1993;Makovsky et al 1996;Nelson et al 1996;Hauck et al 1998), it has become accepted that convergence, exhumation and extrusion proceed in an overall steady-state manner and are directly linked with melting and plutonism (e.g.…”

mentioning

confidence: 98%

Kinematic dilatancy effects on orogenic extrusion

Grasemann

Edwards

Wiesmayr

2006

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We undertake kinematic modelling to explore the role of volume increase in a slab extruding from an orogenic wedge with constant or decreasing slab width. Using a dilatancy term, we modify the velocity gradient tensor dependent on the stretching-rate factor, kinematic dilatancy and vorticity number. We use this to explore the previously largely ignored role of volume change in kinematic evolution of extrusive flow, considering area change for non-isochoric flow types with no deformation in the intermediate direction. By keeping individual parameters constant for geologically simple scenarios (e.g. finite strain, steady-state flow) we examine the interdependence of the reciprocal parameters (kinematic vorticity and dilatancy number) and note model situations where degrees of freedom are limited. These interdependent parameters thereby provide a set of rules for integrating and modelling real field data. In particular we observe that for extrusion flow with a constant slab (or 'channel') width, degrees of freedom in kinematic vorticity and volume change at given finite strains are very restricted. We compare scenarios of low and high strain and low and high volume change on anatexis (related to partial melting of fertile sedimentary rocks and release of water upon crystallization) for different parts of the Himalaya.

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Time relationships between magmatism, tectonics and metamorphism in three plutonic belts in Southern Tibet: new K-Ar data

Cited by 22 publications

References 15 publications

Contrasting metamorphic and geochronologic evolution along the Himalayan belt

Contrasting metamorphic and geochronologic evolution along the Himalayan belt

Constraints on the India-Asia Convergence: Paleomagnetic Results from Ninetyeast Ridge

Kinematic dilatancy effects on orogenic extrusion

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